Method of color photography



Dec. 14, 1954 F. G. BEACH METHOD OF COLOR PHOTOGRAPHY Filed Jan. 2, 1952Fig.2

Frederiqk GZBeaeh JTN V EN TOR. BY @3 3? (gal fl 'ORNEYS United StatesPatent METHOD OF COLOR PHOTOGRAPHY Frederick G. Beach, New York, N. Y.

Application January 2, 1952, Serial No. 264,479

2 Claims. (Cl. 95-2) This invention relates to a method of colorphotography, and more particularly to color photography of a scene whichis illuminated by both natural light and artificial light.

In photographing interior scenes by the use of artificial light of themazda type, wherein the scene is also illuminated by daylight enteringthrough a window or the like, the photographer is faced with thedifficult problem of balancing the color temperatures of the two typesof light so as to obtain light of the correct type for the film which heis using. Naturally, if he is using color film intended for use withartificial light, the higher color temperature of the outdoor lightwould result in incorrect rendition of colors in the finishedphotograph. On the other hand, the use of color film intended foroutdoor use in the presence of artificial lighting again causesincorrect color rendition.

There are, of course, various types of artificial lighting equipmentsuch as blue lamps which are intended to give an illumination closelyresembling daylight, but such lamps are available in a rather smallnumber of sizes and types, and it is, therefore, not convenient to usethem in many cases. It is also undesirable to blank out the daylightentering the scene, since it provides a good source of illumination, andits presence is also helpful if the scene being photographed is toappear completely natural. This is particularly true if the window orthe like is visible in the scene which is being photographed.

It has been suggested that filter material in large sheets could beapplied to the windows appearing in the scene so as to bring theadmitted daylight to the correct color temperature, but such largesheets are quite expensive and are difficult to apply without theirpresence being obvious, and also without objectionable streaks andrefiections being apparent. In the case of a moving object such as atrain, where it might be desirable to take interior color photographsfor advertising or other purposes, the application of filter material insheets is even more impractical, since they can be applied and removedonly while the train is stopped, whereas if they are used inside, theirpresence is apparent, as pointed out above.

I have found that the various difficulties explained above can bereadily overcome by the use of a strippable lacquer type of coatingwhich is sprayed or brushed on the glass of the windows or otherdaylight admitting means, this lacquer containing an appropriatecoloring agent giving it the property of converting the colortemperature of the admitted daylight to approximately the colortemperature of the artificial light. This permits the use of color filmintended for use with artificial illumination and eliminates undesirableeffects resulting from daylight entering the scene.

It is therefore an object of my invention to provide a method of colorphotography of an interior scene illuminated both by daylight enteringthrough a window or the like and by artificial illumination, wherein thecolor temperature of the admitted daylight is changed so as to matchapproximately the color temperature of the artificial light, this beingaccomplished by applying to the window glass an adherent lighttransmitting coating colcred so as to convert the color temperature ofthe admitted daylight approximately to the color temperature ofartificial light, after which the scene is photographed with color filmof the indoor type, that is, color film intended for use with artificiallight.

Another object of the invention resides in the providing 2,697,038Patented Dec. 14, 1954 ice of a photographic method as referred toabove, wherein the coating applied to the window pane is readilystrippable so that it can be easily removed after photographing thescene.

These and other objects of the invention will be more apparent from astudy of the following specification when considered in conjunction withthe accompanying drawing, wherein:

Figure l is a perspective view showing the use of my new photographicmethod in photographing the interior of a railroad car; and Figure 2 isa detail sectional view of a portion of a window pane to which a coatinghas been applied in accordance with my invention.

in referring now to Figure l of the drawing, there is shown a portion ofthe interior of railroad car with a camera 10 and source of artificialillumination 11 arranged for photographing the scene. The scene to bephotographed includes windows 12 through which daylight enters, and itwill be seen that the color temperature of the admitted daylight must bechanged in order for indoor type color film to be used successfully inthe camera 10. i accomplished this change in the color temperature ofthe admitted daylight by applying to the windows 12 a suitable lacquercoating, either by spraying or brushing, which coating contains coloringwhich causes it to change the color temperature of the admitted daylightto match approximately the color temperature of the artificial lightcoming from source 11.

lldggure 2 shows the window at 12 and the coating at It is desirablethat the lacquer which is applied to the window glass or other materialbe readily strippable after the scene has been photographed, so that thechange in the color of the admitted daylight is only accomplishedtemporarily, and the scene can readily be restored to its originalstate. Various types of lacquers can be used in the practice of theinvention, and they can be sprayed on the window or brushed thereon. Thefollowing are examples of lacquer compositions which are useful in thepractice of the invention. in each of these examples a clear solution ismade up after which coloring matter is added to provide the desiredfiltering action.

Example 1 A clear lacquer is made up of the following:

Per cent Acetone 39.5 Ethyl acetate 30. Methyl Cellosolve 20. EthylLactate 10. Surface active agent .5

To this solvent mixture there is added 10% by weight of a celluloseacetate containing about 38-41% acetyl. Where the lacquer is to be usedfor spraying I prefer to use a cellulose acetate having a viscosity ofabout 57 centipoises (cps), while for brushing a higher viscositycellulose acetate is used, for example one having a viscosity in a rangeof 350-500 cps.

To the clear lacquer there is added the following coloring agents, thepercentages being by weight of the lacquer:

Per cent Quercetin 6.4- Plasto Brown 2RS 1.3 Artisil Direct Red 3BP 2.2

Plasto Brown ZRS is commercially available from National AnilineDivision, Allied Chemical and Dye Corp, 40 Rector St., New York 6, N.Y., and is an unsulfonated mono azo dye. Artisil Direct Red 3131 hascolor index 234 and is obtainable from Sandoz Chemical Works, Inc, 61-63Van Dam St., New York 13, N. Y. See Technical Manual and Year Book,American Association of Textile Chemists and Colorists, vol. XXVHI,1952, p. 256. See also the 1939 yearbook, p. 335.

Example 2 A clear lacquer is made up containing:

For spraying it is preferred to use a low viscosity cellulose acetatebutyrate having a viscosity of about 24 cps., while for brushing it ispreferred to use a cellulose acetate butyrate having a viscosity in thevicinity of 450 cps.

The coloring agents set forth in Example 1 are added to the clearlacquer as in the first example.

Example 3 A solvent mixture is made up as follows:

Per cent Acetone 33.5 Ethyl acetate 12. Cellosolve acetate 12. Ethyllactate 4. Butyl alcohol 8. Toluol 20. Surface active agent .5

To the solvent mixture thus prepared there is added about by weight ofcellulose acetate propionate containing about 33% propionate and 13%acetyl.

The same coloring agents set forth in Example 1 are then added to theclear lacquer.

In this example a cellulose acetate propionate having a viscosity ofabout 42 cps. is used for a sprayable composition, whereas one with ahigher viscosity, say about 680 cps., is used for a brushablecomposition.

Various types of surface active agents may be used in the formulationset forth above, for example aerosol OT (dioctyl sodium sulfosuccinate),diglycol laurate, nacconol NR (alkyl aryl sulfonate), aerosol AY (diamylester of sulfosuccinic acid), and artic syntex (a substituted amide). I

Various other types of coating compositions suitable for the purposes ofthis invention can be made up by those skilled in the art. It will berecognized that the solvents used in the lacquer should provide balanced4 composition with a smooth evaporation curve. The surface active agentprovides the desired ready strippability of the coating.

It will be seen that the use of such an easily applied and removedcoating in color photography is a great convenience, particularly Wherethe scene being photographed is the interior of a moving vehicle, suchas a train, where it would be impractical to provide any type ofexterior means to achieve the same object, and where it is not desiredto alter permanently the scene.

While the lacquer formulae which I have set forth are the best known tome, it Will be recognized that other formulations may be made up toaccomplish the same purpose, and I therefore do not desire to be limitedto the use of these particular formulae. My invention resides in theconcept explained hereinabove as a method of taking interior colorphotographs, and is susceptible to numerous variations which Will beobvious to any one skilled in the art. It is my intention to cover allsuch variations coming within the inventive concept as set forth in theappended claims.

I claim:

1. A method of photographing in color an interior scene illuminated bothby daylight entering through a window or the like and by artificialillumination, comprising applying to the window a solution of astrippable film forming composition containing coloring which changesthe color temperature of the admitted daylight to match approximatelythe color temperature of the artificial illumination, which solution onevaporation of the solvent forms an adherent light transmitting solidsheet, and photographing the scene on color film intended for use withartificial light, said coloring comprising quercetin, Plasto Brown 2R5and Artisil Direct Red 331.

2. A method according to claim 1, wherein said solution comprises alower alkyl ester of cellulose in solution in a quick drying solventmixture containing a surface active agent.

References Cited in the file of this patent UNITED STATES PATENTS OTHERREFERENCES Metty, Blue Windows, American Cinematographer, Nov. 1941,page 517.

Number

1. A METHOD OF PHOTOGRAPHING IN COLOR AN INTERIOR SCENE ILLUMINATED BOTHBY DAYLIGHT ENTERING THROUGH A WINDOW OR THE LIKE AND BY ARTIFICIALILLUMINATION, COMPRISING APPLYING TO THE WINDOW A SOLUTION OF ASTRIPPABLE FILM FORMING COMPOSITION CONTAINING COLORING WHICH CHANGESTHE COLOR TEMPERATURE OF THE ADMITTED DAYLIGHT TO MATCH APPROXIMATELYTHE COLOR TEMPERATURE OF THE